Following I'll list the steps I've tried. Please, let me know if this (steps 6 and 7) is the behavior of "p2ized" products, or if this behavior may be an issue.

1. Generate the repository (using the Eclipse Product export wizard or adding p2 metatada generator tags in build.properties for headless build)
2. Use director app to install (p2ize) the product (.product) and all required features3. Open the just p2ized product4. Go to Help->Software Updates (my product and all features are being listed in "Installed Softwares" tab)
5. If I select any installed feature/product and then click on "Update...", immediately an information dialog opens saying "There is nothing to update" (my update site did not received any request as well)
6. In "Available Software" tab, there are no URLs listed in order to find updates of my product7. In the same tab (Available Software), if I click on "Manage Sites..." there is nothing listed as well

I was opened my features.xml contents and verified that the tags "<url> <update ... /> <discovery ... /> </url>" seems to be ok.